What is a fish?

Fish are aquatic animals that live in water and typically have gills, scales, and fins. They are a diverse group of vertebrates found in both freshwater and saltwater environments around the world. Fish play a vital role in aquatic ecosystems and are an important food source for humans and other animals. There are thousands of species of fish, ranging from tiny minnows to large sharks. Many people also keep fish as pets in aquariums.